Berberine inhibits intestinal carcinogenesis by suppressing intestinal pro-inflammatory genes and oncogenic factors through modulating gut microbiota.

backgroundThe role of Berberine (BBR) in colorectal cancer (CRC) and gut microbiota has begun to appreciate. However, there was no direct evidence confirm that the gut microbiota regulated by BBR could inhibit CRC. This report investigated the effect of stool from BBR treated subjects and its effect on CRC.

methodsA mouse model for CRC was developed using azoxymethane (AOM) and dextran sulfate sodium (DSS). Intestinal tissue from affected mice were used to determine the efficacy of BBR against CRC. Stool samples were collected for the 16s rRNA gene sequencing and fecal microbiota transplantation (FMT). Finally, the mechanism of gut microbiota from BBR treated mice on CRC was explored using immunohistochemistry, RNA-Sequencing, quantitative RT-PCR, and western blot analyses.

resultsBBR significantly reduced intestinal tumor development. The richness of gut microbiota were notably decreased by BBR. Specifically, the relative abundance of beneficial bacteria (Roseburia, Eubacterium, Ruminococcaceae, and Firmicutes_unclassified) was increased while the level of bacteria (Odoribacter, Muribaculum, Mucispirillum, and Parasutterella) was decreased by BBR treatment. FMT experiment determined that the mice fed with stool from BBR treated AOM/DSS mice demonstrated a relatively lower abundance of macroscopic polyps and a significantly lower expression of β-catenin, and PCNA in intestinal tissue than mice fed with stool from AOM/DSS mice. Mechanistically, intestinal tissue obtained from mice fed with stool from BBR treated AOM/DSS mice demonstrated a decreased expression of inflammatory cytokines including interleukin 1β (IL-1β), tumor necrosis factor-α (TNF-α), C-C motif chemokine 1 (Ccl1), Ccl6, and C-X-C motif ligand (Cxcl9). In addition, the NF-κB expression was greatly suppressed in mice fed with stool from BBR treated AOM/DSS mice. Real-time PCR arrays revealed a down-regulation of genes involved in cell proliferation, angiogenesis, invasiveness, and metastasis in mice fed with stool from BBR treated AOM/DSS mice.

conclusionsStool obtained from BBR treated AOM/DSS mice was able to increase colon length while simultaneously decreasing the density of macroscopic polyps, cell proliferation, inflammatory modulators and the expression of NF-κB. Therefore, it was concluded that suppression of pro-inflammatory genes and carcinogens factors by modulating gut microbiota was an important pathway for BBR to inhibit tumor growth in conventional mice.